Image pickup apparatus, lens apparatus, and image pickup system

ABSTRACT

A lens apparatus is detachable from an image pickup apparatus. The lens apparatus includes a controller configured to communicate with the image pickup apparatus in synchronization with a first signal. A communication contains a plurality of blocks in the same cycle of the first signal. The controller transmits information of a first time period to the image pickup apparatus, and prohibits a communication of an m-th block from starting before the first time period passes after a communication of an n-th block starts or ends where n is an integer equal to or larger than 1 and m is an integer larger than n.

TECHNICAL FIELD

The present invention relates to an image pickup apparatus, a lensapparatus, and an image pickup system.

BACKGROUND ART

A contrast type autofocus (referred to as a “TVAF” hereinafter) has beenconventionally known and configured to move a focus lens so that thesharpness (focus signal) of a signal obtained from an image sensor canbecome maximum. A lens interchangeable type camera system has also beenknown in which an image pickup apparatus (camera body), such as adigital still camera and a digital camera, generates a focus signal, anda focus lens is driven in an interchangeable lens that is attached toand detachable from the camera body. It is necessary for the TVAFcontrol in this lens interchangeable type camera system to manage thegenerating timing of the focus signal and the driving timing of thefocus lens.

Patent Literature (“PLT”) 1 discloses a method of setting the drivingtiming of the focus lens in the TVAF control in this lensinterchangeable type camera system. PLT 2 proposes a method oftransmitting a busy signal from an interchangeable lens to a camera bodywhen the interchangeable lens cannot communicate or cannot execute acommand from the camera body.

CITATION LIST Patent Literature

-   [PTL 1] Japanese Patent Laid-Open No. 2009-258718-   [PTL 2] Japanese Patent Laid-Open No. 7-306434

SUMMARY OF INVENTION Technical Problem

In the lens interchangeable camera system in PLT 1, each interchangeablelens attachable to the camera body has a different opticalcharacteristic, and it is thus difficult to properly provide the TVAFcontrol for all interchangeable lenses. PLT 2 generates a busy signalhaving a different length for each predetermined timing, and the controlmay be lost in a variety of lens control in synchronization with avertical synchronizing signal (or its integer times) due to a loweredcommunication speed and a random communication timing.

The present invention provides an image pickup apparatus, a lensapparatus, and an image pickup system, in which the lens apparatus canbe properly corrected.

Solution to Problem

A lens apparatus according to the present invention is detachable froman image pickup apparatus. The lens apparatus includes a controllerconfigured to communicate with the image pickup apparatus insynchronization with a first signal. The communication contains aplurality of blocks in the same cycle of the first signal. Thecontroller transmits information of a first time period to the imagepickup apparatus, and prohibits a communication of an m-th block fromstarting before the first time period passes after a communication of ann-th block starts or ends where n is an integer equal to or larger than1 and m is an integer larger than n.

Further features and aspects of the present invention will becomeapparent from the following description of exemplary embodiments withreference to the attached drawings.

Advantageous Effects of Invention

The present invention can provide an image pickup apparatus, a lensapparatus, and an image pickup system, in which the lens apparatus canbe properly corrected.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of a lens interchangeable type camera systemaccording to first and second embodiment of the present invention.

FIG. 2 is a timing chart of a communication between a lens microcomputerand a camera microcomputer illustrated in FIG. 1 according to the firstembodiment.

FIG. 3 is a flowchart of a TVAF control illustrated in the camera systemillustrated in FIG. 1 according to the first and second embodiments.

FIG. 4 is a flowchart for explaining detailed controls of the lensmicrocomputer and the camera microcomputer in a wobbling stepillustrated in FIG. 3 according to the first and second embodiments.

FIG. 5 is a timing chart of the focus control according to the first andsecond embodiment of the present invention.

FIG. 6 is a timing chart of a communication between the lensmicrocomputer and the camera microcomputer illustrated in FIG. 1according to the second embodiment.

DESCRIPTION OF EMBODIMENTS

FIG. 1 is a block diagram of a lens interchangeable type camera system(image pickup system or optical apparatus) according to the presentinvention. The camera system includes a lens unit (lens apparatus) L100and camera body C100 (image pickup apparatus or optical apparatus). Thelens unit L100 is detachably attached to the camera body C100.

The lens unit L100 includes an image pickup optical system, a lensmicrocomputer (lens controller) L106, a zoom actuator L107, and a focusactuator L108.

The image pickup optical system includes a plurality of optical lensunit (optical elements), and forms an optical image of an object. Theimage pickup optical system according to this embodiment includes, inorder in the incident direction of the object image, a first fixed lensL101, a magnification varying lens L102, a diaphragm L103, a secondfixed lens L104, and a focus lens L105. The first fixed lens L101 andthe second fixed lens L104 are maintained stationary. The magnificationvarying lens (zoom lens) L102 moves in the optical axis direction forvarying a magnification. The diaphragm L103 adjusts a light quantity.The focus lens L105 serves to correcting an image plane fluctuationassociated with the magnification variation, and to provide focusing. InFIG. 1, each lens unit has only lens but actually may have one or morelenses.

The lens microcomputer L106 communicates with a camera microcomputerC106 in the camera body C100 at a timing suitable for an image pickuptiming. Thereby, the TVAF control becomes easier. In the TVAF, thecamera body C100 determines a driving amount of the focus lens L105 byevaluating the in-focus state of the image pickup plane for eachpredetermined cycle, and instructs the lens unit L100 to drive the focuslens L105. An in-focus state is again evaluated at the next timing, anda similar operation is performed but at this time the reliability of thefocus information degrades if the lens driving timing is notsynchronized.

More specifically, the camera microcomputer C106 and the lensmicrocomputer L106 performs a fixed-length packet communication at atiming synchronized with a vertical synchronizing signal (verticalsynchronizing communication). A first communication from the lensmicrocomputer L106 to the camera microcomputer C106 as a first block ofthe packet communication is used to transmit a position of the focuslens L105, an aperture value of the diaphragm L103, a position of thezoom lens L102, and operating information. A second communication fromthe camera microcomputer C106 to the lens microcomputer L106 is used asa second block of the packet communication to transmit a focus controlcommand (for motor driving, etc.) such as a target defocus amount, aresult calculated based upon information received in the firstcommunication, etc.

The first communication and the second communication constitute aplurality of blocks contained one each in the same cycle of the firstsignal that is the vertical synchronizing signal (VD) or its integertimes, and are bidirectional communications performed between the cameramicrocomputer C106 and the lens microcomputer L106. It is sufficientthat at least two blocks exist in the same cycle in the first signal,and the number is not limited. In this embodiment, the firstcommunication is an initial communication and the second communicationis the last communication in the vertical synchronizing period.

The first communication and the second communication communicate otherinformation, such as various status information set by a user through abutton, a dial, and a switch (not illustrated in FIG. 1), and thediaphragm and zoom driving commands.

The lens microcomputer L106 includes a lens AF controller L1061. Thelens AF controller L1061 controls focusing in accordance with a targetposition of the focus lens L105 determined by the camera AF controllerC1061. The lens AF controller L1061 provides a zoom tracking controlconfigured to move the focus lens L105 based upon zoom tracking data (azoom tracking cam) stored in the lens microcomputer L106 in themagnification variation. This configuration prevents an image planefluctuation (blur) associated with the magnification variation.

The zoom actuator L107 moves the magnification varying lens L102, andthe focus actuator L108 moves the focus lens L105. Each of the zoomactuator L107 and the focus actuator L108 includes an actuator, such asa stepping motor, a DC motor, an oscillatory motor, and a voice coilmotor.

The camera body C100 includes an image sensor C101, a CDS/AGC/ADconverter C102, a camera signal processor C103, a display unit C104, arecorder C105, and a camera microcomputer C106.

The image sensor C101 is a photoelectric converter, such as a CCD sensorand a CMOS sensor, and outputs an analogue signal by photoelectricallyconverting an object image. The image sensor C101 may be provided oneeach for each of three primary colors of red (R), green (G), and blue(B).

The CDS/AGC/AD converter C102 samples an output of the image sensorC101, gain-controls and digitally converts the sampled output.

The camera signal processor C103 performs various image processing foran output signal from the CDS/AGC/AD converter C102, and generates animage signal. The camera signal processor C103 includes an AF signalprocessor (focus signal generator) C1031. The AF signal processor C1031generates a focus signal by extracting a high frequency component or abrightness difference component generated from the high frequencycomponent in the output signal from a pixel in an area used for a focusdetection in an output signal from all pixels derived from the imagesensor C101 and the CDS/AGC/AD converter C102. The focus signal isreferred to as a contrast evaluation value signal, and represents thesharpness (contrast state) of an image generated based upon the outputsignal from the image sensor C101. The sharpness changes according to afocus state of the image pickup optical system and consequently, thefocus signal represents the focus state of the image pickup opticalsystem.

The display unit C104 displays an image signal from the camera signalprocessor C103, and the recorder C105 records an image signal from thecamera signal processor C103 in a recording medium, such as a magnetictape, an optical disk, and a semiconductor memory.

The camera microcomputer (image pickup apparatus controller) C106controls the focus actuator L108 in the lens unit L100 based upon theoutput from the camera signal processor C103, and moves the focus lensL105 in the optical axis direction. This operation is performed mainlyby the camera AF controller C1061 in the camera microcomputer C106. Adetailed operation of the camera AF controller C1061 will be describedlater.

The camera body C100 includes a power supply unit (battery) and a powerswitch (not illustrated), and whether power is supplied to eachcomponent in the camera body C100 can be selected. The lens unit L100 isprovided with the power from the camera body C100 through a power supplyline (not illustrated).

First Embodiment

FIG. 2 is a timing chart of a communication between the lensmicrocomputer L106 and the camera microcomputer C106. In FIG. 2, “power”has an ON (high) or OFF (low) state when a user operates a power switch(not illustrated) in the camera body C100. “VD” represents a verticalsynchronizing signal. A “communication” represents a signal transmittedfrom the lens microcomputer L106 or the camera microcomputer C106. A“focus actuator” represents a driving state of the focus actuator L108.

When the power is supplied by the operation of the power switch, thecamera microcomputer L106 generates the VD after a time period t21, andstarts an initial communication PI after a time period t22. The initialcommunication PI is a communication initially performed after the poweris turned on or the lens unit L100 is attached to the camera body C100.When a bidirectional fixed-length packet communication is performed attimings synchronized with the VD, the initial communication PI that hasa format different from that of each of other subsequent communicationsis performed in a first one cycle (1V).

Subsequent to the next cycle, a communication that includes two blocksof the first communication P1 and the second communication P2 isperformed in the first one cycle (1V). The time period t22 from theleading edge of the VD to a leading edge of the initial communication PIcan be set to an arbitrary timing based upon the image signal storagetiming of the image sensor C101, but a delay time period to the VD needsto be always constant.

The initial communication PI according to this embodiment transmits atleast following three pieces of information from the lens microcomputerL106 to the camera microcomputer C106 but it is sufficient according tothe present invention that at least one piece of information iscontained.

First information is information of a first time period (a standby timeperiod within a cycle or an intra-cycle standby time period) from astart (leading edge) or end (trailing edge) of the first communicationP1 to a start (leading edge) of the second communication P2 within thesame cycle. The first information corresponds to a time period t23 inFIG. 2. Now assume a plurality of blocks contained in the same cycleinclude n-th (n is an integer equal to or larger than 1) and m-th (m isan integer larger than n). Then, the lens microcomputer L106 transmitsinformation of the intra-cycle standby time period to the cameramicrocomputer C106, and maintains a time period from the start or end ofthe communication of the n-th block to the start of the communication ofthe m-th block in the same cycle not to be shorter than the intra-cyclestandby time period. In other words, the communication of the m-th blockin the same cycle is prohibited from starting before the intra-cyclestandby time period passes after the communication of the n-th blockstarts or ends. The standby time period is provided because it takes atime to process plural information in each block communication (packetcommunication), this is similar to another standby time period.

Second information is information of a second time period (out-of-cyclestandby time period or out-of-cycle standby time period) from a start orend of the communication of the last block (second communication P2) tothe first communication P1 as a first block communication in the nextcycle. The second information corresponds to a time period t24 in FIG.2. The lens microcomputer L106 transmits the information of theout-of-cycle standby time period to the camera microcomputer C106, andmaintains a time period from the start or end of the communication ofthe last block in one cycle to the start of the communication of thefirst block in the next cycle not to be shorter than the out-of-cyclestandby time period. In other words, the communication of the firstblock in the next cycle is prohibited from starting before theout-of-cycle standby time period passes after the communication of thelast block starts or ends in one cycle.

Third information is information of a third time period (actuatorstandby time period) from a start or end of the second communication P2to a driving start of the focus actuator L108. The third informationcorresponds to a time period t25 in FIG. 2. Now assume that a pluralityof blocks contained in the same cycle contain n-th block (n is aninteger equal to or larger than 1). Then, the lens microcomputer L106transmits information of the actuator standby time period to the cameramicrocomputer C106. After the communication of the n-th block starts orends, and before the actuator is ready to be driven in the same cycle,the lens microcomputer L106 is prohibited from receiving a command ofstarting driving the actuator. In other words, the lens microcomputerL106 is prohibited from instructing the actuator to drive before theactuator standby time period passes after a communication of an n-thblock starts or ends where n is an integer equal to or larger than 1.

In the initial communication PI, status information that is not affectedby a state, such as a communication format, a communication speed, acorresponding function, and an individual identification information,with which the lens unit L100 and the camera body C100 are compatible.

In the lens interchangeable type camera system, a computing speed and adata amount to be processed of the lens microcomputer L106 are differentaccording to a type of the lens unit L100. For example, an inexpensivemicrocomputer has a low computing speed because the microcomputerutilizes a reduced operational clock for reducing power consumption. Thedata amount to be processed varies due to the function of the lens unitL100, such as automatic zooming, AF, image stabilizing, diaphragmcontrol, ND filter control, and built-in telecommunication control, andthe precision of each function, and a processing speed is consequentlydifferent. In other words, among the time periods t23, t24, and t25, theprocessing contents and processing time periods of the lensmicrocomputer L106 are different according to the type of the lens unitL100. If the camera microcomputer C106 provides a communication througha control by designating the driving time without considering thedifference of the processing time period, etc. the control may be lostand, for example, the actuator inaccurately moves. Accordingly, thecamera microcomputer C106 provides a communication and a lens control byconsidering the intra-cycle standby time period, the out-of-cyclestandby time period, and the actuator standby time period.

Now assume that a cycle of the VD is set to T, such as 16.67 ms. Then, atotal of the first time period and the second time period satisfiest23+t24<=T so as not to exceed the cycle of the first signal. When thisconditional expression cannot be satisfied, the camera microcomputerC106 extends a communication period.

Referring now to FIGS. 3 to 5, a description will be given of the focuscontrol (TVAF control) performed by the lens microcomputer L106 and thecamera microcomputer C106.

FIG. 3 is a flowchart of an overview of the TVAF control. This procedureis mainly executed by the camera AF controller C1061 in the cameramicrocomputer C106 in accordance with a computer program. The cameramicrocomputer C106 (camera AF controller C1061) controls driving and aposition of the focus lens L105 through communications with the lensmicrocomputer L106 (lens AF controller L1061).

In FIG. 3, in Step 301, the camera microcomputer C106 determines whetherthe current TVAF mode is a wobbling mode. If so the flow moves to theStep 302, and if not the flow moves to Step 308.

In Step 302, the camera microcomputer C106 performs a wobbling operationso as to wobble the focus lens L105 with the predetermined amplitude,and determines whether it is in-focused or if not determines whichdirection an in-focus point exists. A detailed operation will bedescribed with reference to FIGS. 4 and 5.

In Step 303, the camera microcomputer C106 determines whether the focuslens L105 reciprocates in the same area a predetermined number of timesbased upon the positional history of the focus lens L105 as a result ofthe wobbling operation in the Step 302. If so, the in-focus isdetermined and the flow moves to Step 306, and if not, the in-focus hasnot yet been determined and the flow moves to Step 304.

In the Step 304, the camera microcomputer C106 determines whether it hasdetermined that the in-focus point exists in the same direction apredetermined number of times based upon the positional history of thefocus lens L105 as a result of the wobbling operation in the Step 302.If so the in-focus direction is determined and the flow moves to Step305 for the mountain-climbing (peak searching) mode, and if not thein-focus direction has not yet been determined and the flow returns tothe Step 301.

In the Steps 306, the camera microcomputer C106 stores a focus signallevel at the in-focus time in a memory (not illustrated), and the flowmoves to Step 307 for the restart determining mode. The restartdetermining mode is a mode configured to determine whether wobbling isagain necessary to determine the in-focus direction (Steps 316 and 317).

In the Step 308, the camera microcomputer C106 determines whether thecurrent TVAF mode is a mountain-climbing mode, and if so the flow movesto Step 309, and if not the flow moves to Step 313.

In the Step 309, the camera microcomputer C106 provides themountain-climbing configured to drive the focus lens L105 at apredetermined speed in which a value of the focus signal increases. Adetailed description of the mountain-climbing operation will be omitted.

In Step 310, the camera microcomputer C106 determines whether theposition of the focus lens L105 (referred to as a “peak position”hereinafter) which provides a maximum value (a value representing thein-focus state of the image pickup optical system) is detected accordingto the mountain-climbing in the Step 309. When the peak position isdetected, the flow moves to Step 311, and if not the flow returns to theStep 301 so as to continue the mountain-climbing mode. When the peakposition is determined in the Step 310, the focus lens L105 is moved tothe peak position so as to execute the in-focus determining mode (Step315).

In the Step 311, the camera microcomputer C106 sets the peak position tothe target position of the focus lens L105. Then, the flow moves to Step312 for the stopping mode.

In the Step 313, the camera microcomputer C106 determines whether thecurrent TVAF mode is the stopping mode, and if so the flow moves to Step314, and if not the flow moves to Step 316.

In the Step 314, the camera microcomputer C106 determines whether thefocus lens L105 has returned to the peak position. If so, the flow movesto the Step 315 for the wobbling mode so as to determine the in-focus,if not the flow returns to the Step 301 so as to continue the stoppingmode.

In the Step 316, the camera microcomputer C106 compares the level of thecurrent focus signal with the level of the focus signal held in the Step306, and determines whether the variation amount is larger than thepredetermined amount. When the variation amount is larger than thepredetermined amount, the flow moves to Step 317 for the wobbling modeso as to determine the in-focus direction, if not the flow returns tothe Step 301 so as to continue the stopping mode.

Referring now to FIGS. 4 and 5, a description will be given of the flowof the control of the camera microcomputer C106 and the lensmicrocomputer L106 in the Step 302 illustrated in FIG. 3.

In FIG. 4, in Step C401, the camera microcomputer C106 determineswhether the current timing for the VD of the image accords with thepredetermined timing of the communication (referred to as “lenscommunication” hereinafter) with the lens microcomputer L106. If so, theflow moves to Step C402, and if not the flow returns to the Step C401for standing by. The timing of the lens communication for the VDcorresponds to the time period t22 in FIG. 2. One condition to determinethis timing contains an elapse of a time period equal to or longer thanthe out-of-cycle standby time period (equal to or longer than the timeperiod t24) after the second communication P2 in just one previouscycle. The camera microcomputer C106 utilizes a time measuring unit,such as an internal timer or counter (not illustrated) so as todetermine the Step C401.

In the Step C402, the camera microcomputer C106 transmits acommunication request to the lens microcomputer L106 so as to start thelens communication (first communication P1).

In Step L401, the lens microcomputer L106 determines whether it hasreceived the communication request transmitted from the cameramicrocomputer C106 in the Step C402, and if so the flow moves to StepL402, and if not the flow returns to the Step L401 for standing by.

In the Step L402, the lens microcomputer L106 resets the internal timerusing the start of the first communication P1 as a trigger, and measuresa delay time period from the start of the lens communication.

In Step L403, the lens microcomputer L106 transmits a reachingprediction result calculated in the previous processing to the cameramicrocomputer C106. This communication corresponds to the firstcommunication P1. The content of the reaching prediction will bedescribed in detail later in Step L408.

In the Step C403, the camera microcomputer C106 receives the reachingprediction result transmitted from the lens microcomputer L106 in theStep L403 in the first communication P1. In the example illustrated inFIG. 5, if the current VD is (4), then the processing corresponds to thetiming (4) of receiving the reaching prediction.

In Step C404, the camera microcomputer C106 determines whether thecurrently available focus signal is valid. In other words, it determineswhether the image signal as the source of the focusing signal has beenstored not in driving the focus lens L105 but in stopping the focus lensL105 at the past target position. If it is valid, the flow moves to StepC405, and if not the flow moves to Step C416.

In the example of FIG. 5, if the current VD is (4), the available focussignal herein is generated from the image signal stored with the VD(2).Since the focus lens L105 is stopped on the close side in the VD(2), thefocus signal generated from the image signal stored in the VD(2) isdetermined valid. If the current VD is (5), then the available focussignal is generated from the image signal stored with the VD(3). Thefocus signal generated from the stored image signal with the VD(3) isdetermined invalid since the focus lens L105 was moved from the infiniteside to the close side in the VD(3).

In the Step C405, the camera microcomputer C106 moves to the Step C406when the previous reaching prediction result received in the Step C403is reachable (when the information representing that the focus lens L105can reach the target position). If not (when the informationrepresenting that the focus lens L105 cannot reach the target position),the flow moves to Step C418.

For example, when the information that is sent from the lensmicrocomputer L106 at the timing of the reaching prediction (4) andrepresents being reachable, it means that the focus lens L105 can reachthe target position until the electric charge used to generate the focussignal with the VD(4) is stored. On the other hand, when the informationthat is sent from the lens microcomputer L106 at the timing of thereaching prediction (4) and represents being unreachable, it means thatthe focus lens L105 cannot reach the target position until the electriccharge used to generate the focus signal with the VD(4) is stored.

When the information representing being unreachable is received in thefirst communication P1, the focus lens L105 is now being driven and itis likely that a sufficient defocus amount cannot be obtained from thenext available focus signal. In order to avoid the malfunction, it isnecessary to delay the cycle of the TVAF control. Hence, the flow movesto Step C418 without moving forward the TVAF control (wobblingoperation), or the TVAF control is restricted.

For example, when receiving the information representing beingunreachable at the timing of the reaching prediction (4) (in the firstcommunication with the VD(4)), the camera microcomputer C106 does nottransmit a driving command of driving the focus lens L105 in the closeside direction at the timing of the target defocus amount (6). Whenreceiving the information representing being reachable in the next firstcommunication (first communication with the VD(5)), the cameramicrocomputer C106 transmits a driving command of driving the focus lensL105 in the close side direction in the second communication with thesame VD(5).

In Step C406, the camera microcomputer C106 determines whether the focuslens L105 is now stopping on the infinite side with respect to thecenter position as the driving center, and if so the flow moves to theStep C407, and if not the flow moves to the Step C410. In the example ofFIG. 5, if the current VD is (4), it is determined that the focus lensL105 is stopped on the infinite side. When the current VD is (6), it isdetermined that the focus lens L105 is stopped on the close side.

In Step C407, the camera microcomputer C106 stores the focus signal onthe close side. When the current VD is (4) in the example of FIG. 5, thefocus signal (2) is stored which was generated from the image signalstored with the VD(2) at which the focus lens L105 is stopped on theclose side.

In the Step C408, the camera microcomputer C106 compares the level ofthe focus signal on the close side stored in the Step C407 with thelevel of the focus signal on the infinite side which was stored in thepast in Step C410, which will be describe later. If the level on theclose side is higher, the flow moves to Step C409, and if not the flowmoves to Step C413. When the current VD is (4) in the example of FIG. 5,the focus signal (2) is compared with the focus signal 0 (notillustrated).

In the Step C409, the camera microcomputer C106 calculates, as a defocusamount on the image pickup plane of the image sensor C101 (image planecenter moving amount), a moving amount in a close side direction of thecenter position that is the driving center of the focus lens L105. Thisdefocus amount is set to a value within the depth of focus.

In the Step C410, the camera microcomputer C106 calculates, as a defocusamount on the image pickup plane (image plane amplitude amount), adriving amount with respect to the center position of the focus lensL105 in the close side direction. Similar to the moving amount of thecenter position, this defocus amount is set to a value within the depthof focus.

In Step C411, the camera microcomputer C106 stores a focus signal on theinfinite side. When the current VD is (6) in the example of FIG. 5, thefocus signal (4) is stored which was generated from an image signalstored with the VD(4) at which the focus lens L105 is stopped on theinfinite side.

In Step C412, the camera microcomputer C106 compares the level of thefocus signal on the infinite side stored in the Step C411 with the levelof the focus signal on the close side which was previously stored in theStep C407. If the level on the infinite side is higher, the flow movesto Step C413, and if not, the flow moves to Step C414. When the currentVD is (6) in the example of FIG. 5, the focus signal (4) is comparedwith the focus signal (2).

In the Step C413, the camera microcomputer C106 calculates, as a defocusamount on the image pickup plane of the image sensor C101 (image planecenter moving amount), a moving amount in an infinite side direction ofthe center position that is the driving center of the focus lens L105.This defocus amount is set to a value within the depth of focus.

In the Step C414, the camera microcomputer C106 calculates, as a defocusamount on the image pickup plane (image plane amplitude amount), adriving amount with respect to the center position of the focus lensL105 in the infinite side direction. Similar to the moving amount of thecenter position, this defocus amount is set to a value within the depthof focus.

In the Step C415, in order to obtain a defocus amount (target defocusamount) calculated in the Steps C409, C410, C413, and C414, the cameramicrocomputer C106 calculates the timing used to actually start drivingthe focus lens L105.

Herein, the timing (drive staring timing) used to start driving thefocus lens L105 is based upon the storage completing timing of an imagesignal of the image sensor C101, and set by considering the aboveactuator standby time period. In addition, this embodiment defines thisdrive starting timing as a delay time period from the start of the firstcommunication. However, the present invention is not limited to thisembodiment, and a delay time period for the vertical synchronizingsignal, a delay time period from the start of the second communication,etc. may be used.

In Step C416, the camera microcomputer C106 calculates the timing usedto predict whether the above target defocus amount is actually obtainedin driving the focus lens L105 at the drive starting timing calculatedin the Step C415. In other words, the lens microcomputer L106 predictswhether the focus lens L105 can reach the target position correspondingto the target defocus amount at the reaching prediction timing that isthe calculated (designated) timing.

Herein, the reaching prediction timing is set based upon the storagestarting timing of the image signal of the image sensor C101. Accordingto this embodiment, this reaching prediction timing is defined by thedelay time period from the start of the above first communication.However, the present invention is not limited to this embodiment, and avertical synchronizing signal, a delay time period from the start of thesecond communication, may be defined.

In Step C417, it is determined whether the current timing accords withthe timing in the lens communication. If so, the flow moves to StepC418, and if not the flow returns to the Step C417 for standing by. Onecondition to determine this timing includes a passage of a time periodequal to or longer than the above intra-cycle standby time period fromthe first communication.

In the Step C418, the camera microcomputer C106 again transmits acommunication request to the lens unit, and starts the lenscommunication (second communication). Herein, the lens microcomputerL106 determines whether the lens microcomputer L106 has received thecommunication request transmitted from the camera microcomputer C106 inthe Step C416, and if so the flow moves to the Step L405, and if not theflow returns to the Step L404 for standing by.

In the Step C419, when the lens communication starts, the cameramicrocomputer C106 transmits information of the target defocus amountcalculated in the Steps C409, C410, C413, and C414 to the lensmicrocomputer L106. The information of the drive starting timing and thereaching prediction timing calculated (designated) in the Steps C415 andC416 are also transmitted to the lens microcomputer L106. If the currentVD is (4) in the example of FIG. 5, this processing corresponds to thetransmission timing of the target defocus amount (6), the drive starttiming (6), and the reaching prediction timing (6). If the reachingprediction result received in the Step C403 is being unreachable, thenthe camera microcomputer C106 transmits the image plane amplitude amountof the value similar to that in the previous communication the imageplane center moving amount of 0 in the target defocus amount (6).

On the other hand, in the Step L405, the lens microcomputer L106receives the target defocus amount, the drive start timing, and thereaching prediction timing transmitted from the camera microcomputerC106 in the Step C419.

In the Step L406, the lens microcomputer L106 calculates an actualdriving amount (or target position) of the focus lens L105 byconsidering the current focus position sensitivity so that the targetdefocus amount received in the Step L405 can be obtained.

In the Step L407, the lens microcomputer L106 calculates a driving speedof the focus lens L105 in accordance with the actual driving amountcalculated in the Step L406.

In the Step L408, the lens microcomputer L106 provides a reachingprediction where the focus lens L105 is driven at the driving speedcalculated in the Step L407 at the drive starting timing received in theStep L405. More specifically, it is predicted whether the predicteddriving amount of the focus lens L105 from the drive starting timing tothe reaching prediction timing received in the Step L405 reaches theactual driving amount (target position) of the focus lens L105calculated in the Step L406. Thus, the lens microcomputer L106 predictswhether the focus lens L105 can reach the target position. The reachingprediction result is transmitted in the first communication from thelens microcomputer L106 to the camera microcomputer C106 in the nextStep L403.

In the Step L409, the lens microcomputer L106 refers to the value of theinternal timer reset in the Step L402, and determines whether the delaytime period from the start of the first communication accords with thedrive starting timing received in the Step L405. If it accords, the flowmoves to the Step L410, and if not the flow returns to the Step L409 forstanding by.

Herein, the drive starting timing is the timing considering a timeperiod (actuator standby time period) necessary for the lensmicrocomputer L106 to finish various operational processing forrealizing the Steps L405 to L408 and another function other thanfocusing not illustrated in FIG. 4.

In the Step L410, the lens microcomputer L106 sets the actual drivingamount found in the Step L406 and the driving speed calculated in theStep L407 to the focus actuator L108, and actually drives the focusL105. When the current VD is (4) in the example of FIG. 5, theprocessing corresponds to the focus driving timing (6).

Thus, this embodiment previously informs the camera microcomputer C106of three types of standby time periods, such as the intra-cycle standbytime period, the out-of-cycle standby time period, and the actuatorstandby time period, necessary for the lens microcomputer L106, andthereby prevent the communication, calculation processing, and theactuator control from being lost even with the interchangeable lenshaving any characteristics.

This embodiment moves the focus lens L105 by repeating the restartdetermination, wobbling, mountain-climbing, stopping, the wobbling, andrestart determination in the TVAF control. Thereby, a focus state can bemaintained so that the focus signal can be always maximum.

Second Embodiment

A description will be given of a second embodiment according to thepresent invention. The configuration of the lens interchangeable camerasystem according to this embodiment is similar to that of the firstembodiment (FIG. 1). The overview of the TVAF control is also similar tothat of the first embodiment (FIGS. 3 to 5). This embodiment isdifferent from the first embodiment in that the timings at which theintra-cycle standby time period, the out-of-cycle standby time period,and the actuator standby time period are transmitted from the lensmicrocomputer L106 to the camera microcomputer C106 and the time periodsare different according to a circumstance.

FIG. 6 is a timing chart of a communication between the lensmicrocomputer L106 and the camera microcomputer C106. A period from theleading edge of the camera power to the initial communication PI issimilar to that of FIG. 2 of the first embodiment. The first embodimenttransmits the intra-cycle standby time period, the out-of-cycle standbytime period, and the actuator standby time period from the microcomputerL106 to the camera microcomputer C106 in the initial communication PI.This embodiment does not transmit each standby time period to the cameramicrocomputer C106 in the initial communication PI. Rather, each standbytime period is sent to the camera microcomputer C106 in the firstcommunication P1. The camera microcomputer C106 sets the timing of eachof starting the second communication, starting the first communicationin the next cycle, and starting driving the actuator based upon eachstandby time period received in the first communication.

In FIG. 6, the camera microcomputer C106 sets a time period t61 basedupon the intra-cycle standby time period received in the firstcommunication. A time period t62 is set based upon the out-of-cyclestandby time period received in the first communication.

Herein, assume that the condition of the lens unit L100 is maintainedfor a while, and each standby time period transmitted in the firstcommunication has the same value for a while. When the lensmicrocomputer L106 has increased processing, for example, due to anoperation of an image stabilization start switch (or another operation)(not illustrated in FIG. 1) etc., the lens microcomputer L106 changeseach standby time period. The camera microcomputer C106 resets a timeperiod between the first communication and the second communication tot61 to t63, and a time period between the second communication and thefirst communication to t62 to t64 based upon the changed intra-cyclestandby time period and out-of-cycle standby time period. The actuatorstandby time period also changes from t65 to t66 when a time periodnecessary to start driving the actuator changes as the focus controlmode changes, etc.

Thus, this embodiment informs the camera microcomputer C106 of the threetypes of standby time periods in the first communication, such as theintra-cycle standby time period, the out-of-cycle standby time period,and the actuator standby time period, necessary for the lensmicrocomputer L106, and can set the standby time period suitable for thecurrent state of the interchangeable lens.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions. For example, a time period from the start of the firstcommunication is set to the intra-cycle standby time period described ineach embodiment, a time period from the end of the first communicationor a time period from the start of the vertical synchronizing signal maybe used. A time period from the start of the second communication is setto the out-of-cycle standby time period but a time period from the endof the second communication or a time period from the start of thevertical synchronizing signal may be used. Moreover, a time period fromthe start of the second communication is set to the actuator standbytime period but a time period from the end of the second communication,a time period from the start or end of the first communication, or atime period from the start of the vertical synchronizing signal may beused.

The present invention is not limited to each embodiment in which thereare two communication blocks in the same cycle and one actuatornecessary to set the standby time period. For example, when the camerabody provides time-consuming processing for a detection, such asdetecting of an image stabilization vector, a third communication block(three communication) is provided after the second communication, andthe vector information may be transmitted from the camera body to theinterchangeable lens in that timing. When the camera body controls animage stabilization lens, it is necessary for the camera body to providethe actuator standby time period for the image stabilization actuator soas to provide the drive starting timing may be provided. The number maybe increased if necessary.

The embodiments of the present invention cover software (computerprogram) used to realize a function of each embodiment or a system usedto supply the software to the image pickup apparatus or lens apparatusincluding a computer directly from a recording medium or through wire orradio transmissions so as to run the program.

This application claims the benefit of Japanese Patent Application No.2012-004545, filed on Jan. 13, 2012, No. 2012-004765, filed on Jan. 13,2012, and No. 2012-127066, filed on Jun. 4, 2012, which are herebyincorporated by reference herein in their entirety.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a lens interchangeable typecamera system, an exchange lens, and a camera body.

REFERENCE SIGNS LIST

-   L100 lens unit (lens apparatus)-   C100 camera body (image pickup apparatus)-   L106 lens microcomputer (lens controller)-   C106 camera microcomputer (image pickup apparatus controller)

1. A lens apparatus detachable from an image pickup apparatus, the lensapparatus comprising a controller configured to communicate with theimage pickup apparatus in synchronization with a synchronizing signal,wherein a communication between the lens apparatus and the image pickupapparatus is a packet communication having a plurality of blocks in acycle of the synchronizing signal, wherein the controller transmitsinformation of predetermined time stored in the lens apparatus to theimage pickup apparatus, and wherein the information of the predeterminedtime is information to prohibit, before the predetermined time passesafter a communication of an n-th block in a specific cycle of thesynchronizing signal starts or ends, a communication of an m-th blockwhich is performed after the communication of the n-th block in thespecific cycle from starting.
 2. A lens apparatus detachable from animage pickup apparatus, the lens apparatus comprising a controllerconfigured to communicate with the image pickup apparatus insynchronization with a synchronizing signal, wherein a communicationbetween the lens apparatus and the image pickup apparatus is a packetcommunication having a plurality of blocks in a cycle of thesynchronizing signal, wherein the controller transmits information ofpredetermined time stored in the lens apparatus to the image pickupapparatus, and wherein the information of the predetermined time isinformation to prohibit, before the predetermined time passes after acommunication of a last block in a specific cycle of the synchronizingsignal starts or ends, a communication of a first block in a next cycleto the specific cycle from starting.
 3. A lens apparatus detachable froman image pickup apparatus, the lens apparatus comprising a controllerconfigured to communicate with the image pickup apparatus insynchronization with a synchronizing signal, and an actuator, wherein acommunication between the lens apparatus and the image pickup apparatusis a packet communication having a plurality of blocks in a cycle of thesynchronizing signal, wherein the controller transmits information ofpredetermined time stored in the lens apparatus to the image pickupapparatus, and wherein the information of the predetermined time isinformation to prohibit, before the predetermined time passes after acommunication of a block in a specific cycle of the synchronizing signalstarts or ends, a command of driving of the actuator from being issuedfrom the image pickup apparatus.
 4. (canceled)
 5. The lens apparatusaccording to claim 1, wherein the controller transmits the informationof the predetermined time to the image pickup apparatus in an initialcommunication that is performed prior to the packet communication. 6.The lens apparatus according to claim 1, wherein the controllertransmits the information of the predetermined time to the image pickupapparatus in a communication of a first block in the specific cycle ofthe synchronizing signal.
 7. An image pickup apparatus from which a lensapparatus is detachable, the image pickup apparatus comprising acontroller configured to communicate with the lens apparatus insynchronization with a synchronizing signal, wherein a communicationbetween the image pickup apparatus and the lens apparatus is a packetcommunication having a plurality of blocks in a cycle of thesynchronizing signal, and wherein the controller receives information ofpredetermined time stored in the lens apparatus from the lens apparatus,and starts, after the predetermined time passes after a communication ofan n-th block in a specific cycle of the synchronizing signal starts orends, a communication of an m-th block which is performed after thecommunication of the n-th block in the specific cycle.
 8. An imagepickup apparatus from which a lens apparatus is detachable, the imagepickup apparatus comprising a controller configured to communicate withthe lens apparatus in synchronization with a synchronizing signal,wherein a communication between the image pickup apparatus and the lensapparatus is a packet communication having a plurality of blocks in acycle of the synchronizing signal, and wherein the controller receivesinformation of predetermined time stored in the lens apparatus from thelens apparatus, and starts, after the predetermined time passes after acommunication of a last block in a specific cycle of the synchronizingsignal starts or ends, a communication of a first block in a next cycleto the specific cycle.
 9. An image pickup apparatus from which a lensapparatus including an actuator is detachable, the image pickupapparatus comprising a controller configured to communicate with thelens apparatus in synchronization with a synchronizing signal, wherein acommunication between the image pickup apparatus and the lens apparatusis a packet communication having a plurality of blocks in a cycle of thesynchronizing signal, and wherein the controller receives information ofpredetermined time stored in the lens apparatus from the lens apparatus,and issues, after the predetermined time passes after a communication ofa block in a specific cycle of the synchronizing signal starts or ends,a command of driving of the actuator to the lens apparatus.
 10. An imagepickup apparatus from which alens apparatus is detachable, the imagepickup apparatus comprising a controller configured to communicate withthe lens apparatus in synchronization with a synchronizing signal,wherein a communication between the image pickup apparatus and the lensapparatus is a packet communication having a plurality of blocks in acycle of the synchronizing signal, wherein the controller receivesinformation of a first time period and a second time period stored inthe lens apparatus from the lens apparatus, and starts, after the firsttime period passes after a communication of an n-th block in a specificcycle of the synchronizing signal starts or ends, a communication of anm-th block which is performed after the communication of the n-th blockin the specific cycle, and wherein the controller starts, after thesecond time period passes after the communication of a last block in thespecific cycle starts or ends, a communication of a first block in anext cycle to the specific cycle, and adjusts the cycle of thesynchronizing signal so as to maintain a total of the first time periodand the second time period to be equal to or smaller than the cycle ofthe synchronizing signal.
 11. An image pickup system comprising a lensapparatus, and an image pickup apparatus from which the lens apparatusis detachable, wherein the lens apparatus comprising a lens controllerconfigured to communicate with the image pickup apparatus insynchronization with a synchronizing signal, wherein the image pickupapparatus comprising an image pickup apparatus controller configured tocommunicate with the lens controller in synchronization with thesynchronizing signal, wherein a communication between the lens apparatusand the image pickup apparatus is a packet communication having aplurality of blocks in a cycle of the synchronizing signal, wherein thelens controller transmits information of predetermined time stored inthe lens apparatus to the image pickup apparatus controller, and whereinthe image pickup apparatus controller starts, after the predeterminedtime passes after a communication of an n-th block in a specific cycleof the synchronizing signal starts or ends, a communication of an m-thblock which is performed after the communication of the n-th block inthe specific cycle.
 12. An image pickup system comprising a lensapparatus, and an image pickup apparatus from which the lens apparatusis detachable, wherein the lens apparatus comprising a lens controllerconfigured to communicate with the image pickup apparatus insynchronization with a synchronizing signal, wherein the image pickupapparatus comprising an image pickup apparatus controller configured tocommunicate with the lens controller in synchronization with thesynchronizing signal, wherein a communication between the lens apparatusand the image pickup apparatus is a packet communication having aplurality of blocks in a cycle of the synchronizing signal, wherein thelens controller transmits information of predetermined time stored inthe lens apparatus to the image pickup apparatus controller, and whereinthe image pickup apparatus controller starts, after the predeterminedtime passes after a communication of a last block in a specific cycle ofthe synchronizing signal starts or ends, a communication of a firstblock in a next cycle to the specific cycle.
 13. An image pickup systemcomprising a lens apparatus, and an image pickup apparatus from whichthe lens apparatus is detachable, wherein the lens apparatus comprisinga lens controller configured to communicate with the image pickupapparatus in synchronization with a synchronizing signal, and anactuator, wherein the image pickup apparatus comprising an image pickupapparatus controller configured to communicate with the lens controllerin synchronization with the synchronizing signal, wherein acommunication between the lens apparatus and the image pickup apparatusis a packet communication having a plurality of blocks in a cycle of thesynchronizing signal, wherein the lens controller transmits informationof predetermined time stored in the lens apparatus to the image pickupapparatus controller, and wherein the image pickup controller issues,after the predetermined time passes after a communication of a block ina specific cycle of the synchronizing signal starts or ends, a commandof driving of the actuator to the lens controller.
 14. An image pickupsystem comprising a lens apparatus, and an image pickup apparatus fromwhich the lens apparatus is detachable, wherein the lens apparatuscomprising a lens controller configured to communicate with the imagepickup apparatus in synchronization with a synchronizing signal, and anactuator, wherein the image pickup apparatus comprising an image pickupapparatus controller configured to communicate with the lens controllerin synchronization with the synchronizing signal, wherein acommunication between the lens apparatus and the image pickup apparatusis a packet communication having a plurality of blocks in a cycle of thesynchronizing signal, wherein the lens controller transmits informationof a first time period and a second time period stored in the lensapparatus to the image pickup apparatus controller, wherein the imagepickup apparatus controller starts, after the first time period passesafter a communication of an n-th block in a specific cycle of thesynchronizing signal starts or ends, a communication of an m-th blockwhich is performed after the communication of the n-th block in thespecific cycle, and wherein the image pickup apparatus controllerstarts, after the second time period passes after the communication of alast block in the specific cycle starts or ends, a communication of afirst block in a next cycle to the specific cycle, and adjusts the cycleof the synchronizing signal so as to maintain a total of the first timeperiod and the second time period to be equal to or smaller than thecycle of the synchronizing signal.
 15. The lens apparatus according toclaim 2, wherein the controller transmits the information of thepredetermined time to the image pickup apparatus in an initialcommunication that is performed prior to the packet communication. 16.The lens apparatus according to claim 3, wherein the controllertransmits the information of the predetermined time to the image pickupapparatus in an initial communication that is performed prior to thepacket communication.
 17. The lens apparatus according to claim 2,wherein the controller transmits the information of the predeterminedtime to the image pickup apparatus in a communication of a first blockin the specific cycle of the synchronizing signal.
 18. The lensapparatus according to claim 3, wherein the controller transmits theinformation of the predetermined time to the image pickup apparatus in acommunication of a first block in the specific cycle of thesynchronizing signal.